The present invention relates generally to open and/or endoscopic deployment of various devices in body tissues, including a patient""s vascular system, using an internally slideable member frictionally anchored within a stationary trocar or introducer. These devices are deployed in various treatments which include balloon occlusion, filtering, aspiration, pressure monitoring, perfusion, and/or cardioplegia delivery.
Various cardiothoracic surgeries, including coronary artery bypass grafting (CABG), heart valve repair or replacement, septal defect repair, pulmonary thrombectomy, atherectomy, aneurysm repair and correction of congenital defects, generally require pulmonary bypass (CPB), and cardiac arrest. Traditionally, these surgeries are performed through a mid-sternotomy incision. Such an open chest approach entails prolonged hospitalization and rehabilitation by the patient due to significant trauma to the chest wall. Minimally invasive surgical procedures which use an endoscopic approach have been developed to reduce the morbidity and mortality of the surgery, eliminating the need for a gross thoracotomy. More specifically, small incisions are made on a patient""s chest wall, often in the intercostal space, to allow insertion of various instruments to reach the heart and great vessels. In a port-access approach during CABG surgery, arterial cannulation for CPB and cardioplegia delivery for cardiac arrest can be achieved by using endoscopic devices and techniques through a minimal access port in the intercostal space.
New devices and methods are therefore desired to facilitate the performance of minimally invasive CABG. Before CPB can be initiated, incisions are made in the right atrium and the aorta to allow insertion of venous and arterial cannulas. It is often difficult, however, to insert a cannula through various tissue layers to reach the aorta, due to its lack of rigidity. Moreover, it is particularly difficult to insert a cannula having a bent distal end through a narrow intercostal passage into the heart or great vessels. In addition, the cannula may be punctured by the sometimes-calcific arterial wall. A need, therefore, exists for a cannula system which provides easy penetration of a bent cannula through a small incision in tissue layers, and protection of the cannula during its deployment in the aorta.
The present invention provides less invasive devices and methods for cannulating body tissues and infusing fluid therein. More specifically, the invention provides a cannula system for aortic cannulation and occlusion in preparation for CPB, and cardioplegia delivery for cardiac arrest. This cannula system comprises a cannula having an elongate tubular member with a proximal end, a flexible distal end, and a lumen therebetween, and a substantially rigid trocar having a proximal end, a distal end, and a lumen therebetween. The distal end of the cannula has a preformed, angled configuration relative to a proximal region, and the angled region is bendable to a substantially linear configuration. The trocar lumen is shaped to receive the elongate tubular member in its linear configuration. The tubular member is slideable through the lumen of the trocar and regains the angled configuration when advanced distally beyond the distal end of the trocar. The preformed, angled configuration of the distal end is typically between 90-140xc2x0, in certain instances generally L-shaped, so that after the cannula is deployed in the aorta, its distal end is substantially parallel to the aortic wall and thus allows fluid, such as oxygenated blood from the CPB machine, to be delivered downstream to the aorta.
In another embodiment, the elongate tubular member of the cannula has an additional lumen extending distally from the proximal end and communicating with a balloon occluder mounted at its distal end. The tubular member may also have a cardioplegia lumen and/or a lumen for receiving oxygenated blood from a CPB machine extending distally from its proximal end and communicating, respectively, with a cardioplegia port and/or an infusion port, located proximal or distal the balloon occluder. The proximal end of the tubular member is adapted for attachment to the CPB machine. The distal end of the tubular member may also carry a retractable blade for incising the aorta before the cannula is inserted and may contain a balloon-protecting sleeve.
Alternatively, the trocar may have an additional lumen extending distally from the proximal end and communicating with a balloon occluder mounted at its distal end. The trocar may also have a cardioplegia lumen and/or a lumen for receiving oxygenated blood from a CPB machine, extending distally from the proximal end and communicating, respectively, with a cardioplegia port and/or an infusion port located proximal or distal to the balloon occluder. In addition, the distal end of the trocar may be equipped with a retractable surgical blade for incising body tissue, therefore, facilitating easy penetration into the body tissue. It will be understood that where the cannula carries a cardioplegia lumen, the trocar may carry a lumen for oxygenated blood, and vice versa. Alternatively, in certain embodiments, the cannula-trocar assembly may carry cardioplegia or oxygenated blood, but not both. In still other embodiments, the cannula or the trocar will carry both cardioplegia and oxygenated blood, and the other will carry neither cardioplegia nor oxygenated blood.
A thin sheath diffuser may be attached to the distal end of the rigid trocar. This allows use of the trocar as an introducer. Instead of or in addition to having a balloon as an arterial occluder, a filter mechanism, made of a semipermeable mesh, may be used to catch aortic plaque emboli, which if allowed to escape downstream, may cause stroke or arterial occlusion of other organs. Alternatively, the balloon occluder may be replaced by a nonpenetrable dam or barrier material deployable on the distal end of the trocar or tubular member.
Another embodiment of the invention provides a slideable cannula system which has a Y-connector attached to the proximal end of the trocar. The Y-connector has an access port and a cannula port. The access port provides insertion of an access mechanism, such as an introducer with a retractable blade, and the cannula port provides insertion of a cannula for fluid and cardioplegia delivery during CABG surgery.
The present invention provides methods for deployment of various devices, including a balloon occluder, an introducer, a filter, an aspirator, a CPB cannula, a light source, a camera, a pressure monitor, an assisting pump, and/or any other devices, into a body tissue. The methods employ a slideable cannula system which has a cannula comprising an elongate member, a proximal end, a distal end, and a lumen therebetween, and a trocar having a proximal end, a distal end, and a lumen shaped to receive the elongate tubular member. The distal end of the cannula has a preformed angle configuration relative to the proximal region. The elongate tubular member is inserted into the trocar followed by insertion of the trocar inserting cannula unit into a body tissue with the trocar maintaining the tubular member in a substantially linear configuration. Alternatively, the trocar is inserted into a body tissue followed by insertion of the elongate tubular member into the lumen of the trocar. The distal end of the tubular member is advanced beyond the distal end of the trocar, wherein the distal end of the trocar member regains its preformed angled configuration.
In minimally invasive CABG surgery, for example, the trocar containing the cannula, as a unit, is introduced through a small port and inserted through various body tissue layers to reach the aorta. In this way, the trocar provides rigidity to the cannula during insertion and protects the cannula, especially the balloon occluder, from being punctured by the sometimes-calcific aortic wall. The methods described above can also be employed in open cardiothoracic surgeries.
In the embodiments where the cannula contains a balloon occluder and a cardioplegia lumen and port, aortic occlusion can be achieved by inflating the balloon occluder and cardioplegic delivery can be achieved through its cardioplegic lumen and port. Alternatively, in the embodiment where the trocar contains the balloon occluder and cardioplegia lumen and port, arterial (particularly aortic) occlusion and cardioplegia delivery can be achieved after the trocar enters the arterial wall. The balloon occluder on the trocar, when inflated, allows positive placement of the occlusion device.
The present invention also provides methods for making an incision in body tissues. In minimally invasive CABG surgery, an aortic incision for CPB cannulation can be achieved by an optional retractable blade carried at the distal end of the rigid trocar. Alternatively, an aortic incision can be achieved by a retractable blade carried at the distal end of the slideable cannula. An access mechanism with surgical blade can also be introduced through the access port of the Y-connector to incise the aorta.